The present invention relates generally to multi-point probe assemblies for testing electronic devices, and more particularly to such a probe assembly having a plurality of probe arms which are brought into electrical contact with signal-receiving and feeding terminals of a small-sized electronic device (wafer) such as an integrated circuit for a flat panel display or the like.
Various types of multi-point test probe assemblies have been developed hitherto for testing electronic devices of the above mentioned type. One example of such a device is disclosed in Japanese Patent Publication No. 54-43354 (corresponding to U.S. application Ser. No. 799,472 filed Feb. 14, 1969).
This prior art test probe assembly, illustrated in FIGS. 1 and 2, is equipped with a plurality of needle-like probe arms 2. Each of these arms have a radially outboard end secured fixedly to a printed board 1, and an intermediate portion which is supported by a combination of a circularly shaped supporting member 4 and a circularly shaped holding member 5 positioned on one of two main surfaces of the printed board 1. As shown in FIG. 1, the probe arms 2 are arranged in an essentially conical formation and at predetermined angular intervals with respect to the center of the printed board 1.
The radially outer end portions of the probe arms are connected to printed lines 6 formed on one surface of the printed board 1 by means of soldering (7). These printed lines 6 extend into through-holes 8 and are connected with pins (terminals) (not shown) of an external electronic-device test system, which are received therein.
The inboard end portions of the probe arms 2 protrude into the space formed inside the holding member 5 in a manner such that probe-points 3 formed at the inboard ends of the probe arms are accurately positioned on a given plane below the lower surface of the holding member 5.
During testing of an electronic device (not shown), the probe points 3 are respectively brought into contact with terminals of the electronic device with a predetermined force and thus establish electrical connections with the device under test.
However, this arrangement has suffered from the drawback that it is difficult to increase the number of the probe arms beyond a predetermined number. That is to say, it is difficult to reduce the interval between the probe arms due to the inherent crowding which results from the above described type of assembly.
More specifically, when coming into contact with the terminals of the electronic device under the above mentioned predetermined force, the probe arms 2 tend to deflect upwardly and inwardly. Accordingly, the distance between the inboard ends of the arms tends to reduce the point where electrical shorts are apt to occur between adjacent arms (particularly between the probe points).
Thus, the prior art test probe assembly has encountered the limitation that it is not suited to testing electronic devices which have a large number of terminals.
A further and more serious problem relates to damage of the terminals of the device under test. When the contact points come into contact with the terminals of the electronic device, due to the horizontal movement which the probe points tend to undergo as a result of the above mentioned arm deflection, deep scratches tend to be formed in the surfaces of the terminals. This problem is particularly prevalent in the case wherein the terminals are made of, or have a coating of, a soft metal such as gold.